(1) Field of the Invention
The present invention relates to a telephone system which is applied to the private branch exchange (PBX) or the key telephone system and which connects an incoming call to an extension terminal responsive to the source address of the call.
(2) Description of the Prior Art
As connecting methods of calls incoming to a PBX, known are methods in which a destination is determined in a line-corresponding fashion (e.g., a direct in-line method in analog lines and a global terminating method in lines of an Integrated Services Digital Network (ISDN) and methods in which a destination identifier is derived at the time of termination from the network and termination is made to an extension terminal corresponding to the identifier (e.g., a dialling-in method in analog lines, a direct in-dialling method in ISDN lines, and a terminating method by private lines). In these methods, each call is connected to a predetermined extension terminal without distinction of area of the source, which may cause troubles in tele-marketing, for example.
In a system in which a PBX 900 serves two groups of extension terminals (ACD group 1 and ACD group 2.) under termination control by an automatic call distribution (hereinafter, referred to as "ACD") system as shown in FIG. 22, if the phone number (key number) of a tele-marketing telephone center is made known to customers as "XXXX-XX-XXXX", then a call from any area will be connected at random to one extension terminal of ACD group 1 or ACD group 2 served by the PBX 900. This prevents invoices from being pigeonholed on the spot in terms of receiving terminals even when a pigeonhole of invoices according to areas is desired. That is, the invoices had to be arranged by area after reception. Alternatively, in an announcement of the phone numbers of the tele-marketing telephone center to the customers, the phone numbers may be announced separately as "XXXX-XX-XXXX" to the customers in the east area of Japan and as "XX-XXX-XXXX" to the customers in the west area.
By doing this, as shown in FIG. 23 a call of a customer (in the east area) who dialed XXXX-XX-XXXX would be connected through the PBX 900 to an extension terminal of the ACD group 1 and a call of a customer (in the west) who dialed XX-XXX-XXXX would be connected through the PBX 900 to an extension terminal of the ACD group 2. Thus, the invoices can be pigeonholed by ACD groups according to the areas of the sources.
However, since customers do not necessarily call a predetermined phone number, customer's call may be connected to a wrong ACD group according to the technique described above. That is, it is a problem to the customers that they are forced to dial a predetermined phone number and it is a problem to the distributor that every call is not necessarily connected to an extension terminal of its associated ACD group.